From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue, 27 May 2014 13:10:16 -0700
From: Nick Owens <mischief@9.offblast.org>
To: 9fans@9fans.net
Message-ID: <20140527201016.GP3763@iota.offblast.org>
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Subject: [9fans] 8l -e
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i was trying to use 8l's '-e' flag today, when i found some
interesting problems.

first, -e doesn't do what it says unless you pass -p, which goes
unmentioned in the manual page. (luckily i read the source).

second, and more importantly, the calls to _tracein/_traceout are
skipped, as in the following disassembly, but i can't determine why. is
there some tool (besides noping with acid) meant to be used to 'turn on'
the tracing calls?

third, when you use -e with -p, prof.$pid files are generated as with
-p, but the prof files are empty. this seems unintentional.

this example is using rc.

; 8l -p -e -o 8.out code.8 exec.8 getflags.8 glob.8 here.8 io.8 lex.8
pcmd.8 pfnc.8 simple.8 subr.8 trap.8 tree.8 var.8 havefork.8 plan9.8
y.tab.8
; acid 8.out
8.out:386 plan 9 executable
/sys/lib/acid/port
/sys/lib/acid/386
acid: asm(setvar)
setvar 0x0000adbb   JMP	setvar+0x7(SB)
setvar+0x2 0x0000adbd	CALL	_tracein(SB)
setvar+0x7 0x0000adc2	SUBL	$0x10,SP
setvar+0xa 0x0000adc5	MOVL	name+0x0(FP),CX
setvar+0xe 0x0000adc9	MOVL	CX,0x0(SP)
setvar+0x11 0x0000adcc	CALL	vlook(SB)
setvar+0x16 0x0000add1	MOVL	AX,v+0xc(SP)
setvar+0x1a 0x0000add5	MOVL	0x4(AX),AX
setvar+0x1d 0x0000add8	MOVL	AX,0x0(SP)
setvar+0x20 0x0000addb	CALL	freewords(SB)
setvar+0x25 0x0000ade0	MOVL	v+0xc(SP),DX
setvar+0x29 0x0000ade4	MOVL	val+0x4(FP),CX
setvar+0x2d 0x0000ade8	MOVL	CX,0x4(DX)
setvar+0x30 0x0000adeb	MOVL	$0x1,0x8(DX)
setvar+0x37 0x0000adf2	ADDL	$0x10,SP
setvar+0x3a 0x0000adf5	RET
setvar+0x3b 0x0000adf6	CALL	_traceout(SB)
setvar+0x40 0x0000adfb	RET
Xasync 0x0000adfc   JMP	Xasync+0x7(SB)
acid:=20

you can see there is a JMP over _tracein and a RET before _traceout.
what gives?


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